The invention relates to yo-yos and in particular to high performance roller bearing yo-yos.
A typical prior art roller bearing yo-yo consists of two disk-like yo-yo halves attached at their center by an axle, and a roller bearing slidably mounted to the axle between the yo-yo halves. FIG. 6 is a cross-section view of a particular prior art roller bearing yo-yo. This yo-yo includes an axle 74, an inner shell 72 fixedly mounted to the axle by axle threaded end 80 screwed into embedded hex nut 82 of inner shell 72. Outer shell 71 is fixedly attached to inner shell 72. Roller bearing 76 is slid onto the axle and is held in place between facing rims 83 of two spacers 75. Facing rims 83 of the two spacers pinch race 84 of the roller bearing between the halves of the yo-yo. The two spacers are located in spacer pockets 73 which are defined by inner shells 72. Facing rims 87 constrain the strings axial travel on the roller bearing to prevent the string from sliding off the edges of the circumferential surface of the bearing.
Prior art roller bearing yo-yos use single loop stringing because multiple loops of string would cause binding between the bearing and spacer faces 87 and between the bearing and starburst region 88. This would prevent the yo-yo from sleeping. In the single loop stringing method, the string is merely looped around the roller bearing. This allows clearance between faces 87, thereby allowing the roller bearing yo-yo to sleep.
However, prior art roller bearing yo-yos have two disadvantages that limit performance as follows: (1) The sliding of the string around the surface of the roller bearing absorbs energy; and (2) the single loop stringing method allows the string to float from side-to-side across the relatively wide circumferential surface of the roller bearing race 85, which is undesirable because the string, not being centered, will tend to rub on facing rims 87 of the spacer and inner shell starburst regions 88.
A yo-yo according to the present invention includes a first yo-yo half defining a first starburst, a second yo-yo half defining a second starburst, and an axle fixedly mounted between said yo-yo halves. The yo-yo also includes a roller bearing fixedly attached to the axle, and a spool fixedly attached to the roller bearing, the spool having a circumferential outer rim with a groove therein. A bearing pocket defines an annular radial gap between each yo-yo half and the outer rim, the gap sufficiently small that a string cannot wedge in the gap.